Continuing on the theme of how capable we are of determining what is meaningful data, and what is statistical noise, check out this survey being conducted by Swiss graduate students. The user is given charts and asked to state whether they are looking at a stock chart or merely a randomly created line graph.
We could do this for hours!
(Found via Marginal Revolution)
Update: Try this a few times and, in the comments, let us know how you did. I'm 4 for 6 in correctly identifying which chart is the 'random walk'.